Galactic Structure and History with chemodynamical models

在接下来的三年里，欧空局的盖亚使命将开始提供大约10亿颗恒星的三维位置和自行样本，比以前的任何目录都大一万倍。与此同时，大规模的光谱测量正在产生有关恒星化学成分和年龄的详细信息。这两个调查是互补的：盖亚运动学告诉我们银河系的现代结构和动力学，而丰度信息揭示了恒星的诞生地。牛津大学在开发化学动力学建模工具方面发挥着主导作用，这些工具用于从这些数据中推断银河系的现今结构和过去的历史。仅在5年前，我们发现径向迁移在塑造银河系中起着关键作用：当恒星经历经过螺旋臂的旋转势时，它们的角动量和银心半径发生了很大的变化，这导致了盘中比以前天真的模型更多的化学混合。然而，对像银河系这样的螺旋星系的定量影响知之甚少。自然地，这个项目包括两个阶段：在最初的1.5年里，主要是理论工作，以提高对径向迁移和盘加热的理解，并将这些改进的模型应用于这个博士项目中期的第一个盖亚数据发布。学生目前的工作计划如下：在2016年1月之前的前三个月学习相关的文献和背景知识，重点是银河系动力学，化学演化和先进的统计方法。此外，学生将接受编程技能培训，特别是C++。在此之后，学生将学习使用组内现有的软件，包括化学动力学模型和我们先进的光谱代码，稍后将为建模提供输入。学生将致力于对所涉及的过程（径向迁移，加热，更好地理解化学富集）进行更好的分析理解，并探索即将发布的盖亚数据预测的可行性和鲁棒性。在这第一阶段，我们已经有了大量的调查数据（远地点，盖亚-ESO，SEGUE，RAVE，GCS等），其用于培训并且可以提供第一见解和出版物。第一个项目将是限制与APOGEE，RAVE和SEGUE调查中的盘结构相关的运动学偏差。在下半年，我们将测量银河系参数和银河系结构对盖亚测量的太阳邻域的详细影响。根据学生在此期间开发的专业知识，技能和兴趣水平，项目范围将在更多的理论工作之间进行调整，以了解我们银河系的物理学，并使用组内现有的工具进行数据分析。

Within the next three years, ESA's Gaia mission will start to provide three-dimensional positions and proper motions a sample of around a billion stars, ten thousand times larger than any previous catalogue. Concurrently, large-scale spectroscopic surveys are producing detailed information on the chemical composition and ages of stars. The two surveys are complementary: the Gaia kinematics tell us about the present-day structure and dynamics of the Galaxy, while the abundance information reveals where stars were born. Oxford plays a leading role in developing the chemodynamical modelling tools used to infer the present-day structure and past history of the Galaxy from such data. Only 5 years ago we discovered that radial migration plays a key role in shaping the Galaxy: when stars experience the rotating potential of a passing spiral arm, they undergo large changes in angular momentum and Galactocentric radius, which induces much more chemical mixing in the disc than previous naive models. Yet, the quantitative effects on spiral galaxies like the Milky Way are poorly known.Naturally, this project encompasses two phases: Mostly theoretical work to improve the understanding of radial migration and disc heating in the first 1.5 years, and application of these improved models to the first Gaia data release mid-term of this PhD project.The current work plan for the student is as follows: Study of the relevant literature and background knowledge for the first three months until Jan 2016, focussing on Galactic dynamics, chemical evolution and advanced statistical methods. Also, the student will be trained in programming skills, in particular C++. After this, the student will learn to use the existing software within the group, including chemodynamic models and our advanced spectroscopic code, which will later provide inputs for the modelling. The student will work on an improved analytic understanding of the involved processes (radial migration, heating, better understanding of chemical enrichment) and explore the viability and robustness of predictions for the imminent Gaia data release. During this first period we already have an abundance of data from surveys (Apogee, Gaia-ESO, SEGUE, RAVE, GCS, etc.), which serve for training and may deliver first insights and publications. A first project will be to constrain kinematic aberrations relating to disc structure in the APOGEE, RAVE, and SEGUE surveys.In the second half we will measure Galactic parameters and detailed effects of Galactic structure on the solar neighbourhood as measured by Gaia. Depending on the level of expertise, skills and interests developed by the student during, the project scope will be tailored between more theoretical work on new ways to understand the physics of our Galaxy, and data analysis using the existing tools within the group.